The invention relates to a torque sensor for calibrating screwing tools such as dynamometric keys or impact screw drivers.
DE 195 02 616 A1 discloses a torque sensor comprising an inner body having an axis with respect to which a torque is to be measured, and an outer annular body which surrounds the inner body coaxially and which is connected with the inner body through radial webs. There is a first type of web which has a relatively large width circumferentially but has relatively small axial dimensions. And there is a second type of web which is relatively narrow circumferentially but has relatively large axial dimensions. Measuring elements are attached to the first type webs.
The prior art torque sensor serves for the measurement of a torque which is transmitted by rotating parts. The annular body is attached to one rotating part by bolts. The inner body is a ring which is attached to the other rotating body, also by means of axial bolts. The driving torque is transmitted through the webs. Measuring elements in the form of strain gauges are arranged on the first type webs, which are circumferentially wide but relatively thin in axial direction. The strain gauges respond to torsion of the first type webs. The second type webs take up axial forces. The torque sensor of DE 195 02 616 A1 has two diametrically opposite wide and thin webs of the first type bearing the measuring elements. Furthermore, there are differently spaced second type webs symmetrical to the first type webs. The measured values are transmitted by wireless means.
There is a need of calibrating screwing tools. This calibration may consist in determining and, if necessary, adjusting the torque at which a dynamometric key releases. It is, however, also desirable to calibrate dynamically operating screwing tools such as impact screw drivers or wrenches, where the torque is measured which is exerted in impact form on a screwed connection.